CN112345606A - Flexible electrode and preparation method and application thereof - Google Patents

Flexible electrode and preparation method and application thereof Download PDF

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Publication number
CN112345606A
CN112345606A CN202011220751.6A CN202011220751A CN112345606A CN 112345606 A CN112345606 A CN 112345606A CN 202011220751 A CN202011220751 A CN 202011220751A CN 112345606 A CN112345606 A CN 112345606A
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electrode
prepared
flexible electrode
flexible
carbon cloth
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冯欢欢
王丽
马星
赵巍维
郑婷婷
张嘉恒
张月月
冯亮
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Shenzhen Graduate School Harbin Institute of Technology
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Shenzhen Graduate School Harbin Institute of Technology
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Abstract

The invention relates to the technical field of flexible electrodes, in particular to a flexible electrode and a preparation method and application thereof. The invention provides a flexible electrode which comprises carbon cloth and a three-dimensional graphene layer which are arranged in a stacked mode. According to the description of the embodiment, the detection sensitivity of the flexible electrode serving as a working electrode to ascorbic acid can reach 1.805 mA/(mol/L); the kit has targeting detection capability on the biological micromolecules, can simultaneously detect three biological micromolecules of ascorbic acid, dopamine and uric acid, and distinguishes the concentrations of the different biological micromolecules; the detection limit of the reagent to uric acid can reach 5 mu M.

Description

Flexible electrode and preparation method and application thereof
Technical Field
The invention relates to the technical field of flexible electrodes, in particular to a flexible electrode and a preparation method and application thereof.
Background
At present, a variety of sensors are widely used in many intelligent detection devices, and are widely applied to industrial production, ocean exploration, environmental protection, medical diagnosis, bioengineering, space development, smart home and the like.
With the development of the times, it is more and more desirable that the sensor also has the characteristics of transparency, flexibility, extensibility, free bending, even folding, portability, and wearability. With the development of flexible substrate materials, flexible sensors capable of meeting the various characteristics are produced on the basis. Currently, the flexible sensors detect some physical parameters, monitoring life health, food safety, pharmaceutical analysis, etc., mainly based on physical interactions. However, the existing flexible sensor has the problem of high detection limit.
Disclosure of Invention
The invention aims to provide a flexible electrode, a preparation method and application thereof, wherein when the flexible electrode is used as a working electrode of a flexible sensor, the detection limit of the flexible sensor can be reduced, and good sensitivity can be displayed on low-concentration small molecular substances.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a flexible electrode which comprises carbon cloth and a three-dimensional graphene layer which are arranged in a stacked mode.
Preferably, gold nanoparticles are also included;
the gold nanoparticles are distributed on the surface of the three-dimensional graphene layer
Preferably, the thickness of the three-dimensional graphene layer is 138-322 nm.
Preferably, the particle size of the gold nanoparticles is 10-200 nm.
The invention also provides a preparation method of the flexible electrode in the technical scheme, which comprises the following steps:
growing a three-dimensional graphene layer on the surface of the carbon cloth by adopting chemical vapor deposition to obtain the flexible electrode;
the chemical vapor deposition time is 5-10 h.
Preferably, the method further comprises depositing gold nanoparticles on the surface of the three-dimensional graphene layer by electrochemical deposition.
Preferably, the reaction gas for chemical vapor deposition is CH4(ii) a The protective gas is H2；
Said H2The feeding rate of (2) is 150-170 mL/min; the CH4Is in the volume of H2And CH4The percentage of the total volume of (A) is 11.1% -16.7%.
Preferably, the temperature of the chemical vapor deposition is 1000-1100 ℃, and the pressure is normal pressure.
Preferably, the conditions of the electrochemical deposition are as follows: the scanning voltage is-0.2-0.8V; the scanning speed is 0.45-0.55V/s; the number of scanning turns is 2-10 turns.
The invention also provides the application of the flexible electrode in the technical scheme or the flexible electrode prepared by the preparation method in the technical scheme in the preparation of a flexible sensor.
The invention provides a flexible electrode which comprises carbon cloth and a three-dimensional graphene layer which are arranged in a stacked mode. Because the oxidation potentials of the three small molecules (ascorbic acid, dopamine and uric acid) are very similar, the oxidation potentials of the three small molecules can be overlapped on an exposed carbon cloth, and the graphene has good catalytic performance and conductivity, and can be negatively shifted to different degrees when the three small molecules are detected, so that the simultaneous detection of the three small molecules is realized by adding the graphene. Meanwhile, the graphene layer with the three-dimensional structure is more favorable for mass transfer and collection of signals of molecular reaction, and the detection sensitivity is improved. According to the description of the embodiment, the detection sensitivity of the flexible electrode serving as a working electrode to ascorbic acid can reach 1.805 mA/(mol/L); the kit has targeting detection capability on the biological micromolecules, can simultaneously detect three biological micromolecules of ascorbic acid, dopamine and uric acid, and distinguishes the concentrations of the different biological micromolecules; the detection limit of the reagent to uric acid can reach 5 mu M;
the invention also provides a preparation method of the flexible electrode, which comprises the following steps: growing a three-dimensional graphene layer on the surface of the carbon cloth by adopting chemical vapor deposition to obtain the flexible electrode; the chemical vapor deposition time is 5-10 h. The preparation method is simple, the graphene and the substrate material are not easy to fall off, the carbon cloth has good flexibility and biocompatibility, and the possibility of later application to organism implantation is provided.
Drawings
FIG. 1 is a flow chart of the preparation of a flexible electrode comprising gold nanoparticles;
FIG. 2 is SEM images of the surface and cross-section of carbon cloth, 1hGSs/CC prepared in comparative example 1, 2hGSs/CC prepared in comparative example 2, 5hGSs/CC prepared in example 1, 7hGSs/CC prepared in example 2 and 10hGSs/CC prepared in example 5;
FIG. 3 is an SEM image of the flexible electrode prepared in examples 2-4;
FIG. 4 is a CV diagram of a sensor prepared by using carbon cloth and 10hGSs/CC as working electrodes in an ascorbic acid solution;
FIG. 5 is a graph (voltage-current diagram) and I-C diagram of cyclic voltammetry characteristics for detecting uric acid using carbon cloth, 1hGSs/CC prepared in comparative example 1, 5hGSs/CC prepared in example 1, 7hGSs/CC prepared in example 2, and 10hGSs/CC prepared in example 5 as working electrodes by cyclic voltammetry;
FIG. 6 is a graph (voltage-current diagram) and I-C diagram of cyclic voltammetry characteristics of dopamine by cyclic voltammetry with carbon cloth, 1hGSs/CC prepared in comparative example 1, 5hGSs/CC prepared in example 1, 7hGSs/CC prepared in example 2 and 10hGSs/CC prepared in example 5 as working electrodes;
FIG. 7 is a graph (voltage-current diagram) and I-C diagram of cyclic voltammetry characteristics of ascorbic acid using carbon cloth, 1hGSs/CC prepared in comparative example 1, 5hGSs/CC prepared in example 1, 7hGSs/CC prepared in example 2, and 10hGSs/CC prepared in example 5 as working electrodes by cyclic voltammetry;
FIG. 8 is a cyclic voltammetry characteristic curve (voltage-current diagram) of a sensor prepared by using carbon cloth and 10hGSs/CC as working electrodes in a mixed solution of ascorbic acid, dopamine and uric acid;
FIG. 9 is a current-voltage diagram (pulse voltammetry) and I-C diagram of a sensor prepared with 7hGSs/CC as the working electrode in ascorbic acid solution;
FIG. 10 is a current-voltage diagram (pulse voltammetry) and I-C diagram of a sensor prepared with 7hGSs/CC as the working electrode in dopamine solution;
FIG. 11 is a current-voltage diagram (pulse voltammetry) and I-C diagram of a sensor prepared by using 7hGSs/CC as a working electrode in uric acid solution;
FIG. 12 is a current-voltage diagram (pulse voltammetry) of a sensor prepared with carbon cloth and 10hGSs/CC as working electrodes in a mixed solution of ascorbic acid, dopamine and uric acid;
FIG. 13 is a current-voltage curve and I-C plot of a sensor prepared using the flexible electrode prepared in example 2 as the working electrode;
FIG. 14 is a current-voltage curve and I-C plot for a sensor made with the flexible electrode made in example 3 as the working electrode;
FIG. 15 is a current-voltage curve and I-C plot for a sensor made with the flexible electrode made in example 4 as the working electrode;
FIG. 16 is a schematic diagram of the detection of the mixed solution of ascorbic acid, dopamine and uric acid by the sensor prepared by using carbon cloth and 10hGSs/CC as working electrodes.
Detailed Description
The invention provides a flexible electrode which comprises carbon cloth and a three-dimensional graphene layer which are arranged in a stacked mode.
In the present invention, the flexible electrode includes a carbon cloth, and the carbon cloth is not limited in any way, and may be a carbon cloth known to those skilled in the art.
In the present invention, the flexible electrode comprises a three-dimensional graphene layer; the thickness of the three-dimensional graphene layer is preferably 138-322 nm, more preferably 200-300 nm, and most preferably 240-280 nm.
In the present invention, the flexible electrode further preferably comprises gold nanoparticles; the particle size of the gold nanoparticles is preferably 10-200 nm, more preferably 50-150 nm, and most preferably 80-120 nm. The gold nanoparticles are preferably distributed on the surface of the three-dimensional graphene layer.
The invention also provides a preparation method of the flexible electrode in the technical scheme, which comprises the following steps:
growing a three-dimensional graphene layer on the surface of the carbon cloth by adopting chemical vapor deposition to obtain the flexible electrode;
the chemical vapor deposition time is 5-10 h.
In the present invention, the reaction gas for chemical vapor deposition is preferably CH4(ii) a The protective gas is preferably H2(ii) a Said H2The feeding rate of (A) is preferably 150-170 mL/min, and more preferably 160 mL/min; the CH4Is in the volume of H2And CH4The percentage of the total volume of (A) is preferably 11.1% to 16.7%, more preferably 12% to 15.5%, most preferably 13% to 14%; the temperature of the chemical vapor deposition is preferably 1000-1100 ℃, more preferably 1020-1080 ℃, and most preferably 1040-1060 ℃; the time is 5-10 h, preferably 2-7 h, and more preferably 5 h; the pressure is preferably atmospheric pressure.
In the invention, the condition parameters of the chemical vapor deposition are adopted, so that the graphene can grow vertically on the surface of the carbon cloth, and a three-dimensional graphene layer can be formed better.
In the present invention, the preparation method further preferably includes depositing gold nanoparticles on the surface of the three-dimensional graphene layer by electrochemical deposition.
In the invention, the scanning voltage of the electrochemical deposition is preferably-0.2-0.8V; the scanning speed is preferably 0.45-0.55V/s, and more preferably 0.5V/s; the number of scanning turns is preferably 2-10 turns, and more preferably 6 turns. In the present invention, the electrolyte used for the electrochemical deposition is preferably a 0.5M aqueous solution of sulfuric acid; the aqueous sulfuric acid solution also preferably includes 0.6mM AuCl4。
In the invention, the three-dimensional graphene layer can provide nucleation sites for the gold nanoparticles, the gold nanoparticles can be uniformly distributed on the graphene by adopting the electrochemical deposition, and the gold nanoparticles can be controlled within the range of 10-200 nm by further controlling the conditions of the electrochemical deposition within the range.
The invention also provides the application of the flexible electrode in the technical scheme or the flexible electrode prepared by the preparation method in the technical scheme in the preparation of a flexible sensor. In the invention, the application is preferably that the three-electrode system prepared by using the flexible electrode as a working electrode is directly used as a flexible sensor. In the present invention, the reference electrode in the three-electrode system is preferably a saturated calomel electrode, and the counter electrode is preferably a platinum electrode.
The following will describe the flexible electrode and the method for making and using the same in detail with reference to the examples, but they should not be construed as limiting the scope of the invention.
Example 1
Vertically growing 3D graphene on the flexible carbon cloth by adopting a chemical vapor deposition method, wherein H2The introduction rate of (2) is 160mL/min, CH4Is in the volume of H2And CH4The percentage of the total volume of the flexible electrode is 11.1%, the temperature is 1100 ℃, the time is 5 hours, a three-dimensional graphene layer (the thickness is 138nm) is obtained, and the flexible electrode is obtained and recorded as 5 hGSs/CC.
Example 2
Reference example 1, except that: the chemical vapor deposition time is 7h, and the carbon cloth with the three-dimensional graphene layer is obtained and is marked as 7 hGSs/CC; meanwhile, gold nanoparticles are deposited on the graphene layer by an electrochemical deposition method, wherein the electrolyte is 0.5M sulfuric acid aqueous solution; the aqueous sulfuric acid solution also included 0.6mM AuCl4(ii) a Scanning voltage is-0.2-0.6V, scanning speed is 0.5V/s, scanning turns are 2 circles, and the flexible electrode is obtained and marked as Au @ 7hGSs/CC (the particle size of the gold nanoparticles is 10-100 nm).
Example 3
Referring to the preparation method of example 2, the only difference is that the number of scanning turns is replaced with 6 turns (the particle diameter of gold nanoparticles is 20 to 150 nm).
Example 4
Referring to the preparation method of example 2, the only difference is that the number of scanning turns is replaced with 10 turns (the particle diameter of gold nanoparticles is 40 to 200 nm).
Example 5
With reference to the preparation method of example 1, except that the chemical vapor deposition time was 10h, a flexible electrode, noted 10 hGSs/CC.
Comparative example 1
Vertically growing 3D graphene on the flexible carbon cloth by adopting a chemical vapor deposition method, wherein H2The introduction rate of (2) is 160mL/min, CH4Is in the volume of H2And CH4The percentage of the total volume of the electrode is 11.1%, the temperature is 1100 ℃, the time is 1h, a graphene layer (the thickness is 138nm) is obtained, and the flexible electrode is obtained and is marked as 1 hGSs/CC.
Comparative example 2
With reference to the preparation method of example 1, except that the chemical vapor deposition time was 2h, a flexible electrode, noted as 2 hGSs/CC.
Test example
SEM test of the surfaces and cross sections of the carbon cloth, the 1hGSs/CC prepared in the comparative example 1, the 2hGSs/CC prepared in the comparative example 2, the 5hGSs/CC prepared in the example 1, the 7hGSs/CC prepared in the example 2 and the 10hGSs/CC prepared in the example 5 is performed, and the test results are shown in figure 2, wherein a to f are surface SEM pictures of the carbon cloth, the 1hGSs/CC prepared in the comparative example 1, the 2hGSs/CC prepared in the comparative example 2, the 5hGSs/CC prepared in the example 1, the 7hGSs/CC prepared in the example 2 and the 10hGSs/CC prepared in the example 5 in sequence, and g to i are the carbon cloth, the 1hGSs/CC prepared in the comparative example 1, the 2hGSs/CC prepared in the comparative example 2, the 5hGSs/CC prepared in the example 1, the cross sections, SEM images of cross sections of 7hGSs/CC prepared in example 2 and 10hGSs/CC prepared in example 5; as can be seen from fig. 2, the carbon cloth fibers in the carbon cloth have smooth surfaces; after 1h of graphene grows on the surface of the carbon cloth, flaky graphene similar to paper sheets appears on the surface of the carbon cloth fiber, when the growth time of the graphene is increased to 2h, the length of the graphene is increased along with the increase of the growth time, and when the growth time is 5-10 h, the graphene layer becomes thicker obviously; according to the SEM image of the cross section, the thickness of the graphene can be obviously increased and the density is obviously increased along with the increase of the growth time of the graphene, and a three-dimensional structure is gradually formed along with the increase of the growth time of the graphene. Meanwhile, the three-dimensional structure can ensure that graphene layers are not stacked but connected with each other, and the electrochemical active area of the modified electrode is greatly increased by the structure.
Performing SEM test on the flexible electrodes prepared in the embodiments 2 to 4, wherein a to c are SEM images of the flexible electrodes prepared in the embodiments 2, 3 and 4 in sequence, as shown in FIG. 3, when the growth time of graphene is 7 hours, graphite forms graphene with a three-dimensional structure on the surface of the carbon cloth fiber, the graphene with the three-dimensional structure provides nucleation sites for nucleation of gold nanoparticles, the nanoparticles are uniformly distributed on the graphene, and the gold nanoparticles are gradually increased and the particle size is gradually increased along with the increase of the number of scanning turns;
a carbon cloth is used as a working electrode, a saturated calomel electrode is used as a reference electrode, a platinum electrode is used as a counter electrode to form a three-electrode system, the three-electrode system is respectively placed in ascorbic acid solutions with the concentrations of 0mM, 1mM, 2mM and 4mM, the test is carried out by adopting a cyclic voltammetry, wherein the scanning voltage is-0.6-0.4V, the scanning rate is 0.05V/s, and the test result is shown in a left graph in fig. 4, wherein curves in the left graph correspond to CV graphs in the ascorbic acid solutions with the concentrations of 0mM, 1mM, 2mM and 4mM in sequence from bottom to top;
the method comprises the following steps of taking 10hGSs/CC as a working electrode, a saturated calomel electrode as a reference electrode and a platinum electrode as a counter electrode to form a three-electrode system, respectively placing the three-electrode system in ascorbic acid solutions with the concentrations of 0mM, 1mM, 2mM and 4mM, and testing by adopting a cyclic voltammetry method, wherein the scanning voltage is-0.6-0.4V, the scanning rate is 0.05V/s, and the test result is shown in a right graph in fig. 4, wherein curves in the right graph correspond to CV graphs in the ascorbic acid solutions with the concentrations of 0mM, 1mM, 2mM and 4mM from bottom to top in sequence;
as can be seen from FIG. 4, the oxidation potential of ascorbic acid was-0.018V when the carbon cloth was used as the working electrode, and the oxidation potential of ascorbic acid was negatively shifted to-0.068V when the carbon cloth was used as the working electrode and 10hGSs/CC was used as the working electrode. The peak current is obviously increased from 0.3424mA of the raw material to 0.80396mA, and compared with carbon cloth, 10hGSs/CC shows larger background current, which shows that the graphene layer improves the electron transfer capability of the electrode;
1hGSs/CC prepared in comparative example 1, 5hGSs/CC prepared in example 1, 7hGSs/CC prepared in example 2 and 10hGSs/CC prepared in example 5 are used as working electrodes, a saturated calomel electrode is used as a reference electrode, a platinum electrode is used as a counter electrode to form a three-electrode system, and the three-electrode system is placed in Ascorbic Acid (AA) solutions with the concentrations of 0.05mM, 0.1mM, 0.2mM, 0.4mM, 0.5mM, 1.0mM, 2.0mM and 4.0mM respectively and tested by a cyclic voltammetry, wherein the scanning voltage is-0.6-0.4V, the scanning rate is 0.05V/s, and the test results are shown in FIG. 5; wherein the left graph is a current-voltage graph (voltage-current graphs in Ascorbic Acid (AA) solutions with concentrations of 0.05mM, 0.1mM, 0.2mM, 0.4mM, 0.5mM, 1.0mM, 2.0mM and 4.0mM in sequence from bottom to top) for detecting uric acid by using the 7hGSs/CC prepared in example 2 as a working electrode and adopting a CV method, and the right graph is an I-C graph obtained by detecting ascorbic acid by using a three-electrode system which is respectively composed of 11hGSs/CC prepared in comparative example 1, 5hGSs/CC prepared in example 1, 7hGSs/CC prepared in example 2 and 10hGSs/CC prepared in example 5 as a working electrode;
as can be seen from fig. 5, the response current of the graphene/carbon cloth electrode to AA gradually increases with the increase of the graphene growth time, and reaches a maximum when the graphene growth time is 7 hours. As can be seen from the I-C diagram, the largest detection sensitivity is obtained by catalyzing AA by 7 hGSs/CC;
1hGSs/CC prepared in comparative example 1, 7hGSs/CC prepared in example 2 and 10hGSs/CC prepared in example 5 are used as working electrodes, a saturated calomel electrode is used as a reference electrode, a platinum electrode is used as a counter electrode to form a three-electrode system, and the three-electrode system is respectively placed in dopamine solutions with the concentrations of 0.001mM, 0.002mM, 0.005mM, 0.01mM, 0.02mM, 0.05mM, 0.1mM, 0.2mM, 0.4mM, 0.8mM and 1.0mM and tested by a cyclic voltammetry, wherein the scanning voltage is-0.6-0.4V, the scanning rate is 0.05V/s, and the test result is shown in FIG. 6; wherein the left graph is a current-voltage graph (voltage-current graphs in dopamine solutions with concentrations of 0.001mM, 0.002mM, 0.005mM, 0.01mM, 0.02mM, 0.05mM, 0.1mM, 0.2mM, 0.4mM, 0.8mM and 1.0mM in sequence from bottom to top) for detecting dopamine by using the 7hGSs/CC prepared in example 2 as a working electrode and adopting a CV method, and the right graph is an I-C graph obtained by detecting dopamine by using a three-electrode system which comprises the 1hGSs/CC prepared in comparative example 1, the 7hGSs/CC prepared in example 2 and the 10hGSs/CC prepared in example 5 as a working electrode;
as can be seen from fig. 6, the response current of the graphene/carbon cloth electrode to dopamine is gradually increased with the increase of the graphene growth time, and reaches a maximum when the graphene growth time is 7 hours. As can be seen from the I-C diagram, the maximum detection sensitivity is obtained by catalyzing DA by 7 hGSs/CC;
respectively taking carbon cloth, 1hGSs/CC prepared in a comparative example 1, 5hGSs/CC prepared in an example 1, 7hGSs/CC prepared in an example 2 and 10hGSs/CC prepared in an example 5 as working electrodes, taking a saturated calomel electrode as a reference electrode and a platinum electrode as a counter electrode to form a three-electrode system, respectively placing the three-electrode system in uric acid with the concentrations of 0.01mM, 0.02mM, 0.05mM, 0.1mM, 0.2mM, 0.4mM, 0.8mM and 1.0mM, and testing by adopting a cyclic voltammetry, wherein the scanning voltage is-0.6-0.4V, the scanning rate is 0.05V/s, and the test result is shown in figure 7; wherein the left graph is a current-voltage graph (the curves from bottom to top correspond to the concentrations of 0.01mM, 0.02mM, 0.05mM, 0.1mM, 0.2mM, 0.4mM, 0.8mM and 1.0mM in sequence) for detecting ascorbic acid by using carbon cloth as a working electrode and adopting a CV method, and the right graph is an I-C graph obtained by detecting uric acid;
as can be seen from fig. 7, the response current of the graphene/carbon cloth electrode to uric acid is gradually increased with the increase of the graphene growth time, and reaches the maximum when the graphene growth time is 5 hours. As can be seen from the I-C diagram, the maximum detection sensitivity of the catalysis of 5hGSs/CC on uric acid is obtained;
as can be seen from the comprehensive graphs of 5-7, the GSs/CC has the maximum sensitivity for detecting three small molecular substances within 7 h. And the lowest detection concentrations for AA, DA and UA were 0.05mM, 0.001mM and 0.005mM, respectively.
A carbon cloth is used as a working electrode, a saturated calomel electrode is used as a reference electrode, a platinum electrode is used as a counter electrode to form a three-electrode system, the three-electrode system is respectively placed in a mixed solution of 0mM (blank solution), 0.2mM and 0.4mM Ascorbic Acid (AA), Dopamine (DA) and Uric Acid (UA) (the concentration ratio of ascorbic acid, dopamine and uric acid is 1: 1: 1), a CHI-760E electrochemical workstation is utilized, a cyclic voltammetry method is adopted for testing (a detection schematic diagram is shown in figure 16), wherein the scanning voltage is-0.6-0.4V, the scanning rate is 0.05V/s, and the test result is shown in a left graph in figure 8 (curves corresponding to concentrations of 0mM, 0.2mM and 0.4mM are sequentially from bottom to top);
a three-electrode system is formed by taking 10hGSs/CC as a working electrode, a saturated calomel electrode as a reference electrode and a platinum electrode as a counter electrode, the three-electrode system is respectively placed in a mixed solution (the concentration ratio of ascorbic acid to dopamine to uric acid is 1: 1: 1) of 0mM (blank solution), 0.2mM and 0.4mM of Ascorbic Acid (AA), Dopamine (DA) and Uric Acid (UA), a CHI-760E electrochemical workstation is utilized, and a cyclic voltammetry method is adopted for testing (a detection schematic diagram is shown in figure 16), wherein the scanning voltage is-0.6-0.4V, the scanning rate is 0.05V/s, and the test result is shown in a right graph in figure 8 (curves corresponding to the concentrations of 0mM, 0.2mM and 0.4mM are sequentially from bottom to top);
as can be seen from fig. 8, when the carbon cloth is used as the working electrode, only two sets of peaks appear, and the redox potentials of AA, DA, and UA overlap due to the close distance, indicating that the three substances cannot be detected simultaneously when the carbon cloth is used as the working electrode; however, three groups of peaks appear when 10hGSs/CC is used as a working electrode, which shows that the 10hGSs/CC can simultaneously detect three substances as the working electrode, and the current signal is obviously increased, and the electrochemical phenomena show that the 10hGSs/CC not only can simultaneously detect three biological small molecules but also can obviously improve the oxidation signals of the three small molecular substances, and obviously improve the sensitivity of the sensor.
A three-electrode system is formed by taking 7hGSs/CC as a working electrode, a saturated calomel electrode as a reference electrode and a platinum electrode as a counter electrode, and the three-electrode system is placed in Ascorbic Acid (AA) solutions of 0.005mM, 0.01mM, 0.02mM, 0.04mM, 0.08mM, 0.1mM, 0.2mM, 0.4mM, 0.8mM, 1.0mM, 2.0mM and 4.0mM and tested by adopting a differential pulse voltammetry method, wherein the test conditions are as follows: the scanning voltage is-0.6-0.4V, the pulse amplitude is 50/n mV, and the pulse width is 0.05 ms; the results are shown in FIG. 9 (curves corresponding to concentrations of 0.005mM, 0.01mM, 0.02mM, 0.04mM, 0.08mM, 0.1mM, 0.2mM, 0.4mM, 0.8mM, 1.0mM, 2.0mM, and 4.0mM, in the order from bottom to top);
as can be seen from FIG. 9, the oxidation potential of ascorbic acid was around-0.1V, the oxidation current increased linearly with the increase in concentration, and a good linear range was obtained in the concentration range of 0.005-0.4 mM;
a three-electrode system is formed by taking 7hGSs/CC as a working electrode, a saturated calomel electrode as a reference electrode and a platinum electrode as a counter electrode, the three-electrode system is placed in 0.002mM, 0.005mM, 0.01mM, 0.02mM, 0.04mM, 0.08mM, 0.1mM, 0.2mM, 0.4mM, 0.8mM, 1.0mM and 2.0mM dopamine (AA) solutions and tested by adopting a differential pulse voltammetry method, and the test conditions are as follows: the scanning voltage is-0.6-0.4V, the pulse amplitude is 50/n mV, and the pulse width is 0.05 ms; the results are shown in FIG. 10 (curves corresponding to concentrations of 0.002mM, 0.005mM, 0.01mM, 0.02mM, 0.04mM, 0.08mM, 0.1mM, 0.2mM, 0.4mM, 0.8mM, 1.0mM, and 2.0mM, in the order of the lower curve to the upper curve);
as can be seen from FIG. 10, the oxidation potential of dopamine is around 0.1V, the oxidation current increases linearly with the increase of the concentration, and a good linear range exists in the concentration range of 0.002-0.4 mM;
a three-electrode system is formed by taking 7hGSs/CC as a working electrode, a saturated calomel electrode as a reference electrode and a platinum electrode as a counter electrode, the three-electrode system is placed in a uric acid (AA) solution with the concentration of 0.004mM, 0.008mM, 0.01mM, 0.02mM, 0.04mM, 0.08mM, 0.1mM, 0.2mM, 0.4mM, 0.8mM, 1.0mM and 2.0mM, and the test is carried out by adopting a differential pulse voltammetry method, wherein the test conditions are as follows: the scanning voltage is-0.6-0.4V, the pulse amplitude is 50/n mV, and the pulse width is 0.05 ms; the test results are shown in FIG. 11 (curves corresponding to concentrations of 0.004mM, 0.008mM, 0.01mM, 0.02mM, 0.04mM, 0.08mM, 0.1mM, 0.2mM, 0.4mM, 0.8mM, 1.0mM, and 2.0mM, in order, from bottom to top);
as can be seen from FIG. 11, the oxidation potential of uric acid is around 0.25V, the oxidation current increases linearly with the increase of the concentration, and a good linear range is obtained in the concentration range of 0.004-0.4 mM;
as can be seen from the graphs in FIGS. 9 to 11, we have obtained the oxidation potentials and linear ranges of the three substances under the condition of single detection of the electrode of 7hGSs/CC, and we have found that the oxidation potentials of the three substances are separated by a certain distance and have the possibility of being detected simultaneously.
A carbon cloth is used as a working electrode, a saturated calomel electrode is used as a reference electrode, a platinum electrode is used as a counter electrode to form a three-electrode system, and the three-electrode system is respectively placed in mixed solutions of 0.1mM Ascorbic Acid (AA), 0.01mM Dopamine (DA) and 0.005-4.0mM Uric Acid (UA) (the concentrations are respectively 0.005mM, 0.01mM, 0.02mM, 0.04mM, 0.08mM, 0.1mM, 0.2mM, 0.4mM, 0.8mM, 1.0mM, 2.0mM and 4.0 mM); and (3) testing by adopting a differential pulse voltammetry under the following test conditions: the scanning voltage is-0.6-0.4V, the pulse amplitude is 50/n mV, and the pulse width is 0.05 ms; the test results are shown in the left panel of FIG. 12 (curves corresponding to concentrations of 0.005mM, 0.01mM, 0.02mM, 0.04mM, 0.08mM, 0.1mM, 0.2mM, 0.4mM, 0.8mM, 1.0mM, 2.0mM, and 4.0mM, in order from bottom to top);
a three-electrode system is formed by taking 10hGSs/CC as a working electrode, a saturated calomel electrode as a reference electrode and a platinum electrode as a counter electrode, and the three-electrode system is respectively placed in mixed solution of 0.1mM Ascorbic Acid (AA), 0.01mM Dopamine (DA) and 0.005-4.0mM uric acid (the concentrations of which are respectively 0.005mM, 0.01mM, 0.02mM, 0.04mM, 0.08mM, 0.1mM, 0.2mM, 0.4mM, 0.8mM, 1.0mM, 2.0mM and 4.0mM) (UA); the test is carried out by adopting a Differential Pulse Voltammetry (DPV) method, and the test conditions are as follows: the scanning voltage is-0.6-0.4V, the pulse amplitude is 50/n mV, and the pulse width is 0.05 ms; the test results are shown in the right graph in FIG. 12 (curves corresponding to concentrations of 0.005mM, 0.01mM, 0.02mM, 0.04mM, 0.08mM, 0.1mM, 0.2mM, 0.4mM, 0.8mM, 1.0mM, 2.0mM, and 4.0mM, in order from bottom to top);
as shown in fig. 12, when the carbon cloth is used as a working electrode, three substances cannot be distinguished, and oxidation peaks of the three substances overlap; when 10hGSs/CC is used as a working electrode, the oxidation potentials of the three substances detected by the DPV are-0.06V, 0.112V and 0.252V respectively. The difference between each two is 0.118V and 0.140V respectively, and the potential difference is large. Therefore, when the 10hGSs/CC is used as a working electrode, the requirements of single detection and simultaneous detection of three substances can be met;
the flexible electrode prepared in example 2 was used as a working electrode, a saturated calomel electrode as a reference electrode, and a platinum electrode as a counter electrode to form a three-electrode system, which was sequentially placed in uric acid solutions having concentrations of 0.002mM, 0.004mM, 0.008mM, 0.01mM, 0.02mM, 0.04mM, 0.08mM, 0.1mM, 0.2mM, 0.4mM, and 0.8mM and tested by Differential Pulse Voltammetry (DPV) under the following test conditions: the scanning voltage is-0.6-0.4V, the pulse amplitude is 50/n mV, and the pulse width is 0.05 ms; the test results are shown in FIG. 13 (curves corresponding to concentrations of 0.002mM, 0.004mM, 0.008mM, 0.01mM, 0.02mM, 0.04mM, 0.08mM, 0.1mM, 0.2mM, 0.4mM, and 0.8mM in the order of the lower curves to the upper curves);
the flexible electrode prepared in example 3 was used as a working electrode, a saturated calomel electrode as a reference electrode, and a platinum electrode as a counter electrode to form a three-electrode system, which was sequentially placed in uric acid solutions having concentrations of 0.005mM, 0.01mM, 0.02mM, 0.04mM, 0.08mM, 0.1mM, and 0.2mM, and tested by a Differential Pulse Voltammetry (DPV) method under the following conditions: the scanning voltage is-0.6-0.4V, the pulse amplitude is 50/n mV, and the pulse width is 0.05 ms; the results are shown in FIG. 14 (curves corresponding to concentrations of 0.005mM, 0.01mM, 0.02mM, 0.04mM, 0.08mM, 0.1mM and 0.2mM in the order from bottom to top);
the flexible electrode prepared in example 4 was used as a working electrode, a saturated calomel electrode as a reference electrode, and a platinum electrode as a counter electrode to form a three-electrode system, which was sequentially placed in Uric Acid (UA) solutions having concentrations of 0.002mM, 0.004mM, 0.008mM, 0.01mM, 0.02mM, 0.04mM, 0.08mM, 0.1mM, 0.2mM, and 0.4mM, and tested by a Differential Pulse Voltammetry (DPV) method under the following test conditions: the scanning voltage is-0.6-0.4V, the pulse amplitude is 50/n mV, and the pulse width is 0.05 ms; the test results are shown in FIG. 15 (curves corresponding to concentrations of 0.002mM, 0.004mM, 0.008mM, 0.01mM, 0.02mM, 0.04mM, 0.08mM, 0.1mM, 0.2mM, and 0.4mM in the order of the lower curve to the upper curve);
as can be seen from FIGS. 13-15, the sensitivity of the electrode pair UA detection increases gradually with the number of scanning cycles as shown in FIG. 13, and reaches as high as 51.7mA/(mol/L) when the number of scanning cycles is 10 as shown in FIG. 15. However, as the number of scan cycles increases, the upper limit at which UA can be detected decreases, i.e., there is no good linear range. Combining all the properties, the electrode has the best performance when the number of scanning turns is 6, as shown in fig. 14, and has both good sensitivity and wide linear range. The probable reason is that excessive gold nanoparticles occupy excessive active sites of graphene when deposited excessively, and in further experiments, the adsorption performance and the catalytic performance of the gold nanoparticles are reduced during catalytic reaction of small molecules. Indicating that depositing a modest amount of gold particles greatly increases their sensitivity.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims (10)

1. A flexible electrode is characterized by comprising a carbon cloth and a three-dimensional graphene layer which are arranged in a stacked mode.
2. The flexible electrode of claim 1, further comprising gold nanoparticles;
the gold nanoparticles are distributed on the surface of the three-dimensional graphene layer.
3. The flexible electrode of claim 1, wherein the thickness of the three-dimensional graphene layer is 138nm to 322 nm.
4. The flexible electrode of claim 2, wherein the gold nanoparticles have a particle size of 10 to 200 nm.
5. A method for preparing a flexible electrode according to any one of claims 1 to 4, comprising the steps of:
growing a three-dimensional graphene layer on the surface of the carbon cloth by adopting chemical vapor deposition to obtain the flexible electrode;
the chemical vapor deposition time is 5-10 h.
6. The method of claim 5, further comprising depositing gold nanoparticles on the surface of the three-dimensional graphene layer using electrochemical deposition.
7. The method of claim 5, wherein the chemical vapor deposition reaction gas is CH4(ii) a The protective gas is H2；
Said H2The feeding rate of (2) is 150-170 mL/min; the CH4Is in the volume of H2And CH4The percentage of the total volume of (A) is 11.1% -16.7%.
8. The method according to claim 5 or 7, wherein the temperature of the chemical vapor deposition is 1000 to 1100 ℃ and the pressure is normal pressure.
9. The method of claim 6, wherein the conditions of the electrochemical deposition are: the scanning voltage is-0.2-0.8V; the scanning speed is 0.45-0.55V/s; the number of scanning turns is 2-10 turns.
10. Use of the flexible electrode according to any one of claims 1 to 4 or the flexible electrode prepared by the preparation method according to any one of claims 5 to 9 in the preparation of a flexible sensor.
CN202011220751.6A 2020-11-05 2020-11-05 Flexible electrode and preparation method and application thereof Pending CN112345606A (en)

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